Seg fault issue

This is a discussion on Seg fault issue within the C++ Programming forums, part of the General Programming Boards category; Hey guys. I am creating a small type and search program and it compiles ok. If I enter the correct ...

  1. #1
    Its hard... But im here swgh's Avatar
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    Seg fault issue

    Hey guys.

    I am creating a small type and search program and it compiles ok. If I enter the correct word it displays the character string fine then terminates. However, if I enter an incorrect word, it freezes and throws a seg-fault. After using the debugger, the error line is the if statement header. Here is the code:

    Code:
    #include <iostream>
    #include <cstring>
    
    // main function - driver //////////////////////////////////////////////////////
    //
    int main ( void )
    {
       int i;
       char *pSearchGrid[][ 2 ] = 
       {
          "pencil", "A writing device",
           "amelle", "One of the Sugababes" ,
           "computer", "Hardware device that uses software" ,
           "phone", "Device that makes and recieves telephone calls" ,
           "picture", "Drawn or computerized image",
           "", "" 
       };
       
       char word[ 80 ];
       
       std::cout << "Enter a word to find: ";
       std::cin >> word;
       
       for ( i = 0; pSearchGrid[ i ][ 0 ]; i++ )
       {
           if ( !strcmp ( pSearchGrid[ i ][ 0 ], word ))
           {
              std::cout << std::endl << pSearchGrid[ i ][ 1 ] << std::endl;
              break;
           }
       }
       
       if ( !*pSearchGrid[ i ][ 0 ] )  // SEG FAULT DEBUG BREAK HERE
       {
          std::cout << word << " not found...\n";
       }
              
       std::cin.get(); // freeze console output window
       std::cin.ignore();
       
       return 0; // return value from int main
    }
    I have looked over it and cannot see why it keeps breaking here. Can you see what I have done wrong? I appreciate any help.
    I'm just trying to be a better person - My Name Is Earl

  2. #2
    The larch
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    Apparently the end terminator "" has a non-null address and doesn't stop the loop where you want to. You probably want to check if the first character of that string is '\0'.
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  3. #3
    Registered User
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    Unless you absolutely need to do it that way, an std::map would be much more appropriate.

  4. #4
    Its hard... But im here swgh's Avatar
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    Quote Originally Posted by anon View Post
    Apparently the end terminator "" has a non-null address and doesn't stop the loop where you want to. You probably want to check if the first character of that string is '\0'.
    Thanks!

    I changed the for loop line to

    Code:
    for ( i = 0; *pSearchGrid[ i ][ 0 ]; i++ )
    and its working now

    And Desolation, we havent covered maps yet but when we do I am sure I will understand your meaning further. Thank you for the advice guys.
    I'm just trying to be a better person - My Name Is Earl

  5. #5
    Kernel hacker
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    Code:
       char *pSearchGrid[][ 2 ] = 
       {
          "pencil", "A writing device",
           "amelle", "One of the Sugababes" ,
           "computer", "Hardware device that uses software" ,
           "phone", "Device that makes and recieves telephone calls" ,
           "picture", "Drawn or computerized image",
           NULL, NULL
       };
    would be a better change, as:
    1. It makes it obvious that it's the end of the list.
    2. Takes up (slightly) less space.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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